---
title: "Reference: Tool Call Filter | Processors"
description: "Documentation for the ToolCallFilter processor in Mastra, which filters out tool calls and results from messages."
---

# ToolCallFilter

The `ToolCallFilter` is an **input processor** that filters out tool calls and their results from the message history before sending to the model. This is useful when you want to exclude specific tool interactions from context or remove all tool calls entirely.

## Usage example

```typescript copy
import { ToolCallFilter } from "@mastra/core/processors";

// Exclude all tool calls
const filterAll = new ToolCallFilter();

// Exclude specific tools by name
const filterSpecific = new ToolCallFilter({
  exclude: ["searchDatabase", "sendEmail"],
});
```

## Constructor parameters

<PropertiesTable
  content={[
    {
      name: "options",
      type: "Options",
      description: "Configuration options for the tool call filter",
      isOptional: true,
    },
  ]}
/>

### Options

<PropertiesTable
  content={[
    {
      name: "exclude",
      type: "string[]",
      description: "List of specific tool names to exclude. If not provided or undefined, all tool calls are excluded",
      isOptional: true,
    },
  ]}
/>

## Returns

<PropertiesTable
  content={[
    {
      name: "id",
      type: "string",
      description: "Processor identifier set to 'tool-call-filter'",
      isOptional: false,
    },
    {
      name: "name",
      type: "string",
      description: "Processor display name set to 'ToolCallFilter'",
      isOptional: false,
    },
    {
      name: "processInput",
      type: "(args: { messages: MastraDBMessage[]; messageList: MessageList; abort: (reason?: string) => never; requestContext?: RequestContext }) => Promise<MessageList | MastraDBMessage[]>",
      description: "Processes input messages to filter out tool calls and their results based on configuration",
      isOptional: false,
    },
  ]}
/>

## Extended usage example

```typescript title="src/mastra/agents/filtered-agent.ts" showLineNumbers copy
import { Agent } from "@mastra/core/agent";
import { ToolCallFilter } from "@mastra/core/processors";

export const agent = new Agent({
  name: "filtered-agent",
  instructions: "You are a helpful assistant",
  model: "openai:gpt-4o",
  tools: {
    searchDatabase,
    sendEmail,
    getWeather,
  },
  inputProcessors: [
    // Filter out database search tool calls from context
    // to reduce token usage while keeping other tool interactions
    new ToolCallFilter({
      exclude: ["searchDatabase"],
    }),
  ],
});
```

## Filtering all tool calls

```typescript copy
import { Agent } from "@mastra/core/agent";
import { ToolCallFilter } from "@mastra/core/processors";

export const agent = new Agent({
  name: "no-tools-context-agent",
  instructions: "You are a helpful assistant",
  model: "openai:gpt-4o",
  tools: {
    searchDatabase,
    sendEmail,
  },
  inputProcessors: [
    // Remove all tool calls from the message history
    // The agent can still use tools, but previous tool interactions
    // won't be included in the context
    new ToolCallFilter(),
  ],
});
```

## Related

- [Guardrails](/docs/v1/agents/guardrails)
